What does Ruth 4:6 mean?
The game Boaz is playing is exquisite. His primary goal is to win the right to redeem Naomi's land from the man who bought it from her husband, marry Ruth, and have a son with Ruth who will re-inherit Naomi's land from Boaz (Ruth 3:9–13). Barring that, he knows Ruth will still get what she wants if this man, more closely related to Naomi's late husband, accepts the same responsibilities.Boaz begins by informing the man who is Naomi's kinsman-redeemer; he has the first right to buy her late husband's land to keep it within the clan; since Naomi has no male heirs, they will not inherit it. With the famine over, there is minor risk for the man—he gets more land for his own sons—and he agrees (Ruth 4:1–4). But then Boaz fills in the final detail: when the redeemer takes the land, he is also to marry Ruth and provide Naomi with an heir.
The unnamed man has several legitimate reasons to refuse the offer because it includes Ruth. Boaz has subtly reminded the man and the crowd that Ruth is a Moabite (Ruth 4:5). She descends from the women who seduced the Israelites from their God and families (Numbers 25:1–9). Boaz knows and respects that Ruth has abandoned her people, culture, and gods (Ruth 1:16–17; 2:11–12). The other man might worry his son's family line will not be able to worship as an Israelite for ten generations (Deuteronomy 23:3–6). Boaz knows the other man probably doesn't want a Moabitess in his house, let alone in his marriage. In the moment, the anonymous relative thinks the arrangement would threaten the inheritance of his sons.
Ruth 1:4 is a bit ambiguous; we don't know if Ruth and Orpah were married to Naomi's sons for ten years or if Naomi and her sons were in Moab for ten years total. Either way, Ruth apparently does not have a child. So, in the best-case scenario, the man would have to support Naomi and Ruth until they died. In a worst-case scenario, Ruth would have a son who would inherit the land at the year of Jubilee, and then Ruth would have more children the man would have to support.
The man is not required by law to marry Ruth and give Naomi an heir. Naomi is the landowner's widow, but she's beyond child-bearing age. More importantly, the man is not her late husband's brother so he is not obligated to a levirate marriage (Deuteronomy 25:5–6). "Levirate" literally refers to "brother." He doesn't qualify. Any pressure he feels is purely tied to public image; Boaz did well to frame the situation around Naomi and her plight. To reject the redemption is to reject Naomi and Ruth's need.
Instead of insulting Ruth, the man uses the second excuse, saying he can't afford the arrangement. The word "impair" can mean "to ruin, spoil, destroy" as in warfare or pestilence. Because he's not legally responsible, he is free to make that decision. Because Boaz wants the responsibility, there is no harm done.
